Hypermedia Glossary Of Genetic Terms
|Chromomere||The term applied by Wilson (1896) to each of the serially aligned granules of a chromosome, best seen when the thread is relatively elongated as in early prophase 1 ofmeiosis(Gk. chroma, colour; meros, part).|
|Chromosome||The term was proposed by Waldeyer (1888) for the individual threads within a cell nucleus (gk. chroma, colour; soma, body). The self-replicating genetic structures of cells containing the cellular DNA that bears in its nucleotide sequence the linear array of genes. In prokaryotes, chromosomal DNA is circular, and the entire genome is carried on one chromosome. Eukaryotic genomes consist of a number of chromosomes whose DNA is associated with different kinds of proteins.|
|Prophase||Strasburger (1884) originally introduced this term for the early stage of nuclear division before (Gk. pro) the chromosomes divide into two chromatids, but from about 1905, with the realization that the chromosomes are double from the beginning of nuclear division, he used the term in the now universally adopted sense of the stage of mitosis or of meiosis I or II before breakdown of the nuclear membrane.
condensation of chromosomes
longitudinal splitting of chromosomes visible
formation of spindle apparatus and fragmentation of nucleus membrane
|Meiosis||The term coined by Farmer and Moore (1905) for the process of two consecutive cell divisions in the diploid progenitors of sex cells. Meiosis results in four rather than two daughter cells (gametes), each with a haploid set of each chromosome pair. In meiosis I the prophase is more complex than that of mitosis. Five different stages can be differentiated: leptotene, zygotene, pachytene, diplotene and diakinesis. Prophase is followed by metaphase I, anaphase I, telophase I and interkinesis. Meiosis II could be described as a haploid mitosis resulting in four haploid gametes.
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